The objective is to identify all relatives of gravidae registered in the Collaborative Project and link their records to facilitate genetic studies of obstetric, pediatric, psychological and sensory data. Although an existing version of the Family Linkage file was adequate for genetical studies, reviews intended to correct supposedly minor flaws uncovered errors, omissions of information, and inconsistencies in format which would have made the file useless for studies in the Malformations and other programs. The file will be completed an applied in familial studies of malformations, and items in other program areas.